Override Jquery client validation on date format

 $(function () {  
   // Replace the builtin US date validation with UK date validation  
   $.validator.addMethod(  
     "date",  
     function (value, element) {  
       var bits = value.match(/([0-9]+)/gi), str;  
       if (!bits)  
         return this.optional(element) || false;  
       str = bits[1] + '/' + bits[0] + '/' + bits[2];  
       return this.optional(element) || !/Invalid|NaN/.test(new Date(str));  
     },  
     "Please enter a date in the format dd/mm/yyyy"  
   );  
 });  

Jquery Unobtrusive validation on hidden field

 <script type="text/javascript">   
 $(function () {   
 var form = $('#[formID]);   
 form.data('validator').settings.ignore = ''; // default is ":hidden".   
 });   
 </script>